In an inserting machine for mass mailing, there is a gathering section where the enclosure material is gathered before it is inserted into an envelope. This gather section is sometimes referred to as a chassis subsystem, which includes a gathering transport with pusher fingers rigidly attached to a conveying means and a plurality of enclosure feeders mounted above the transport. If the enclosure material contains many documents, these documents must be separately fed from different enclosure feeders. Each of the enclosure feeders feeds or releases a document at the appropriate time such that the trailing edge of the document released from the enclosure feeder is just slightly forward of a moving pusher finger. Timing and velocity control of all feeders are critical because during the feeding process a document is under the control of both an enclosure feeder motor and the gathering transport motor.
Currently one or more long endless chains driven by a single motor are used to move the pusher fingers in order to gather the enclosure material released from the enclosure feeders and send the gathered material to an envelope insertion station. It is preferable that the spacing of the pusher fingers attached to the conveying chain is substantially the same as the spacing of the enclosure feeders mounted above the conveying chain. A typical pitch for the enclosure feeders is 13.5" (343 mm). Depending on the length of the document stacked on a feeder, the feeder is given a "go" signal to release an enclosure document on the conveying belt at an appropriate time.
After the machine has run a prolonged period of time, the conveying chain begins to wear and stretch, as is the case with steel chains. Consequently, the timing that is predicted can be off a substantial amount from one end of the machine to the other. The amount can be accumulated through tolerances, and the stretch can reach an amount that equals the smaller document that may be fed. For example, in a 20 station machine with a length of 22.5 feet, the 2% stretch would equate to 5.4 inches. This is greater than the smallest document to be fed.
Therefore, it is desirable to provide a method and apparatus to improve the timing between the transport and the feeders which compensates for chassis chain stretch so that the distance between a pusher finger and the trailing edge of a fed enclosure document is appropriate.